This invention relates to circuit breakers, and, more particularly, to a motor control center circuit breaker assembly.
Motor control centers, such as described in U.S. Pat. No. 5,424,911 entitled Compact Motor Controller Assembly, contain several components related to electric motor operation such as electric contactors, circuit breakers, power supply transformers, disconnect switches and the like.
An electric disconnect switch is described in U.S. Pat. No. 4,785,145 entitled Modular Electrical Disconnect Switch, and one such circuit breaker is described in U.S. Pat. No. 4,884,164 entitled Molded Case Circuit Interrupter. The use of a circuit breaker for both motor protection and switch functions is described in U.S. Pat. No. 4,945,450 entitled Modular Electric Switch-Circuit Breaker Assembly. A unit combining both circuit breaker and contactor functions is found in U.S. Pat. No. 5,657,193 entitled Electronic Control Module for Motor Controller Units.
When several electric devices are combined within a common enclosure, it is important that the enclosure interior remain inaccessible when the electrical devices are operating to prevent damage to both equipment and personnel. The aforementioned U.S. Pat. No. 5,424,911 employs an external interlock device to insure that the circuit breaker operating handle is in the OFF position prior to providing access to the interior of the motor controller unit. When a circuit breaker is used within non-interlocked motor controller units, it is important to view the ON/OFF positions of the circuit breaker operating handle, prior to accessing the motor controller interior.